Firmware Upgrade problem

Upgrading firmware on several wrt54g's. One of the units was a v1 new in the box. I attempted to upgrade original firmare (1.7.xxxx) to 2.4.xxxx. The upgrade completed and said successful. After clicking successful the screen froze and never changed. I could not get back into the setup page. Tried for an hour, reset, power down, everything. I finally left the unit alone, unplugged, for about 2 days before I got back to it. Started the unit and it was working again. I used the linksys program to upgrade the unit to the latest 3.x.x.x and once again the unit froze. It will not respond or allow tftp?
Any clues?